1. Technical Field
The present invention relates to pneumatic tools, and more particularly to a pneumatic tool using a single controller for both forward/reverse switching and speed adjustment.
2. Description of Related Art
A conventional pneumatic tool primarily comprises a housing that has an air supplying channel and an exhausting channel, a motor installed in the housing, an output shaft extending out the housing and driven by the motor, and a control that controls the operation of the motor. The control comprises a button exposed outside the housing, and a pushing rod driven by the button. When a user presses the button, the pushing rod opens an air inlet valve installed in the air supplying channel, so as to allow gas in the air supplying channel to flow through a specific route to drive the motor.
Such a pneumatic tool is extensively used with a sleeve mounted around its output shaft for screwing or unscrewing a screw or a nut. Stating differently, most pneumatic tools allow users to change the rotational direction of their output shafts. Therefore, the control further comprises a forward/reverse switching lever for users to operate, and a switching valve driven by the forward/reverse switching lever to change the air route. For facilitating both left-handed and right-handed users to smoothly operate the forward/reverse switching lever, the forward/reverse switching lever for a conventional pneumatic tool allows the user to reposition its operating paddle. For repositioning the paddle, the user has to first pull the forward/reverse switching lever outward and then rotate it. After released, the forward/reverse switching lever is returned by a spring basing it. The mechanism is thus complicated in terms of design and inconvenient to use.
The control for the known pneumatic tool usually has a rotation-rete adjuster, which comprises a dial for users to operate and change a gas flow that drives the motor, thereby adjusting the rotation rate of the output shaft. It is clear that the control of the conventional pneumatic tool uses two different controllers (i.e. the foregoing forward/reverse switching lever and the dial of the rotation-rete adjuster) for users to perform forward/reverse switching (namely changing the rotational direction of the output shaft) and adjust the rotation rate of the output shaft. The control is thus structurally complicated and inconvenient to use.